1. Field of the Invention
This invention relates to cross beam rotors for helicopters which utilize composite rotor spars.
2. Description of the Prior Art
Heretofore helicopters having cross beam spars of composite material were attached to the rotor hub by a large number of bolts because these bolts were required to transmit torque between the rotor drive shaft and the blades and hence were subjected to heavy shear loads. Also the lug areas where the bolts passed through the material of the composite spars were required to be reinforced to transmit this hub to spar torque. Due to the large number of bolts required too many critical longitudinal fibers of the blade spars were interrupted by the bolt holes, requiring many cross patterned layers of composite build-up to strengthen these areas as a shear lug definition and for bearing of the bolts. This is an expensive time-consuming, weight-penalty operation.